1. Field of the Invention
The present invention relates to carbon dioxide injection for tertiary hydrocarbon recovery. More particularly, the present invention relates to portable power generators that can be used for producing the carbon dioxide gas for injection into a hydrocarbon-bearing formation. The present invention also relates to systems and methods whereby the carbon dioxide gas can be produced from the exhaust of a combustion turbine.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
The world's power demands are expected to rise 60% by 2030. The U.S. Energy Information Administration (EIA) estimates that fossil fuels will account for more than 75% of the world energy use by 2040 even though the share of coal will decline from 28% in 2012 to 22% in 2040, according to International Energy Outlook 2016 by EIA.
The U.S. currently produces approximately 9.1 million barrels of oil per day as of March 2016. Most of the oil fields in the United States are declining in oil recovery productivity. It has been proven that carbon dioxide can be used for enhanced oil recovery so as to increase oil recovery productivity in the declining fields. The Department of Energy estimates that up to 137 billion barrels of “stranded” oil can be recovered using carbon dioxide for enhanced oil recovery.
There are tens of thousands of depleted oil and natural gas reservoirs around the world, which collectively possess significant amounts of petroleum resources that cannot currently be extracted using conventional extraction techniques. For example, in a typical oil reservoir, only about 30% of the underground oil is recovered with primary production methods. An additional approximately 20% may be accessed by “secondary recovery” techniques, such as water flooding. In recent years, “tertiary recovery” techniques have been developed to recover additional oil from depleted reservoirs. Such tertiary recovery techniques include chemical injection, and gas injection. Using current methods, these tertiary techniques allow for an additional 20% or more of the original oil-in-place (OOIP) to be recovered.
Gas injection is one of the most common tertiary techniques with CO2 being one of the preferred gases. In particular, carbon dioxide injection into depleted oil reservoirs has received considerable attention owing to its ability to mix with crude oil. Since the crude oil can be miscible with carbon dioxide, the injection of carbon dioxide renders the oil substantially less viscous and more readily extractable.
Carbon dioxide in quantities sufficiently large enough for commercial exploitation generally has come from three sources. One such source is the naturally occurring CO2 found underground in areas such as Colorado, New Mexico, Wyoming, Mississippi, and other areas this also includes the CO2 that is removed from natural gas streams in order to meet pipeline delivery specifications. A second source is that resulting from by-products of the operation of a primary process, such as the manufacture of ammonia or hydrogen from methane. A third source is found in the exhaust gases from burning of various hydrocarbon fuels. Regardless of the source one of the largest problems that is faced by carbon dioxide users is the problem of transportation from the place of production to the point of use.
Problems exist within the current carbon dioxide pipeline infrastructure in that extensions into potentially productive areas are costly and somewhat limited due to the availability of high purity carbon dioxide. Even in areas that have relatively close proximity to an existing carbon dioxide pipeline, extensions to potential producing areas are costly and time-consuming. The single greatest problem is the lack of commercial quantities of carbon dioxide in close proximity to the oil fields that are in need of this resource to produce the remaining reserves that are recoverable by using the tertiary recovery methods. This problem is exacerbated when the field is remote from an existing carbon dioxide pipeline and/or is not of sufficient size to justify the costly extension of the pipeline infrastructure. Because a reservoir in an oilfield undergoing tertiary recovery will begin to recycle quantities of carbon dioxide that are recovered along with the tertiary oil, the need for carbon dioxide in the tertiary oil-producing respectively will diminish significantly over time. This necessitates the recovery of pipeline infrastructure capital costs quickly.
Currently, carbon dioxide is present in low concentrations, such as within the flue gas from power generation facilities. These plants are found all over the United States and can be fired from a variety of hydrocarbon sources, including coal, fuel oil, biomass, and natural gas. Unfortunately, these facilities are most often located near large water sources due to their need to use this water for cooling during the power production process. In addition, these are very large facilities with a long economic life. There are many oil fields that are not located within a sufficiently close proximity to such existing large power generation facilities in order to attempt to economically utilize a carbon capture technology and pipeline delivery method to provide the carbon dioxide to the oilfields that have this need.
Combustion turbine generators operating in combined cycle are known in the prior art. Virtually all of these combustion turbine generators operating in combined cycle are used in electrical generating facilities, such as power plants. Modern large combustion turbine generators operating in combined cycle have highly efficient heat rates. As a result of this high efficiency, a smaller amount of carbon dioxide is produced per unit of power production. In the past, less efficient combustion turbines operating in combined cycle were also developed. These prior combustion turbines operating in combined cycle required a larger amount of fuel in order to produce the same amount of power. However, these earlier less efficient combustion turbines operating in combined cycle actually produced a larger amount of carbon dioxide per unit of power. Current trends are to continue the improvement of technology with combustion turbines operating in combined cycle so that they become increasingly efficient maximizing the amount of power produced relative to the amount of fuel consumed. As such, the earlier less efficient combustion turbines operating in combined cycle have been relegated to a variety of other uses, such as in ships and industrial facilities.
Heretofore, the combustion turbines operating in combined cycle have found little application in the oilfield. To the extent that these combustion turbine generators operating in combined cycle have been utilized in the oilfield, the carbon dioxide output has been typically discharged to the atmosphere and have only been employed to provide electricity for oilfield operations.
In the past, various patents have been issued relating to the production of carbon dioxide for tertiary hydrocarbon recovery. For example, U.S. Pat. No. 4,499,946, issued on Feb. 19, 1985 to Martin et al., provides a portable, above-ground system and process for generating combustion gases and for injecting the purified nitrogen and carbon dioxide at controlled temperatures into a subterranean formation so as to enhance the recovery thereof. The system includes a high-pressure combustion reactor for sufficient generation of combustion gases at the required rates and at pressures up to about 8000 p.s.i. and temperatures up to about 4500° F. The reactor is water-jacketed and lined with refractory material to minimize soot formation.
U.S. Pat. No. 4,741,398, issued on May 3, 1988 to F. L. Goldsberry, shows a hydraulic accumulator-compressor vessel using geothermal brine under pressure as a piston to compress carbon dioxide-rich gas. This is used in a system having a plurality of gas separators in tandem to recover pipeline quality gas from geothermal brine. A first high pressure separator feeds gas to a membrane separator which separates low pressure waste gas from high pressure quality gas. A second separator produces low pressure waste gas. Waste gas from both separators is combined and fed into the vessel through a port at the top as the vessel is drained for another compression cycle.
U.S. Pat. No. 4,824,447, issued on Apr. 25, 1989 to F. L. Goldsberry, describes an enhanced oil recovery system which produces pipeline quality gas by using a high pressure separator/heat exchanger and a membrane separator. Waste gas is recovered from both the membrane separator and a low pressure separator in tandem with the high pressure separator. Liquid hydrocarbons are skimmed off the top of geothermal brine in the low pressure separator. High pressure brine from the geothermal well is used to drive a turbine/generator set before recovering waste gas in the first separator. Another turbine/generator set is provided in a supercritical binary power plant that uses propane as a working fluid in a closed cycle and uses exhaust heat from the combustion engine and geothermal energy of the brine in the separator/heat exchanger to heat the propane.
U.S. Pat. No. 4,899,544, issued on Feb. 13, 1990 to R. T. Boyd, discloses a cogeneration/carbon dioxide production process and plant. This system includes an internal combustion engine that drives an electrical generator. A waste heat recovery unit is provided through which hot exhaust gases from the engine are passed to recover thermal energy in a usable form. A means is provided for conveying exhaust gases coming out of the waste heat recovery unit to a recovery unit where the carbon dioxide is extracted and made available as a saleable byproduct.
U.S. Pat. No. 7,753,972, issued on Jul. 13, 2010 to Zubrin et al., discloses a portable energy system for enhanced oil recovery. This is a truck mobile system that reforms biomass into carbon dioxide and hydrogen. The gases are separated. The carbon dioxide is sequestered underground for enhanced oil recovery and the hydrogen used to generate several megawatts of carbon-free electricity.
U.S. Patent Publication No. 2008/0283247, published on Nov. 20, 2008 to Zubrin et al., shows a portable, modular apparatus for recovering oil from an oil well and generating electric power. This system includes a chassis to support a fuel reformer, a gas separator, a power generator, and/or a compressor. The fuel reformer module is adapted to react a fuel source with water to generate a driver gas including a mixture of carbon dioxide gas and hydrogen gas. The gas separator module is operatively coupled to the reformer module and is adapted to separate at least a portion of the hydrogen gas from the rest of the driver gas. The power generator module is operatively coupled to the gas separator module and is adapted to generate electric power using a portion of the separated hydrogen gas. The compressor module is operatively connected to the reformer module and is adapted to compress a portion of the driver gas and to eject the driver gas at high pressure into the oil well for enhanced oil recovery.
U.S. Patent Publication No. 2009/0236093, published on Sep. 24, 2009 to Zubrin et al., shows a method for extracting petroleum by using reformed gases. This method includes reforming a fuel source by reaction with water to generate driver gas and injecting the driver gas into the oil well. The reforming operation includes causing the combustion of a combustible material with ambient oxygen for the release of energy. A reforming reaction fuel and water is heated with the energy released from this heating process. This is at a temperature above that required for the reforming reaction in which the fuel and water sources are reformed into the driver gas.
U.S. Patent Publication No. 2004/0314136, published on Dec. 16, 2010 to Zubrin et al., discloses an in-situ apparatus for generating carbon dioxide gas at an oil site for use in enhanced oil recovery. The apparatus includes a steam generator adapted to boil and superheat water to generate a source of superheated steam, as well as a source of essentially pure oxygen. The apparatus also includes a steam reformer adapted to react a carbonaceous material with the superheated steam and the pure oxygen, in an absence of air, to generate a driver gas made up of primarily carbon dioxide gas and hydrogen. A separator is adapted to separate at least a portion of the carbon dioxide gas from the rest of the driver gas to generate a carbon dioxide-rich driver gas and a hydrogen-rich fuel gas. A compressor is used for compressing the carbon dioxide-rich driver gas for use in enhanced oil recovery.
U.S. Patent Publication No. 2011/0067410, published on Mar. 24, 2011 to Zubrin et al., teaches a reformation power plant that generates clean electricity from carbonaceous material and high pressure carbon dioxide. The reformation power plant utilizes a reformation process that reforms carbonaceous fuel with super-heated steam into a high-pressure gaseous mixture that is rich in carbon dioxide and hydrogen. This high-pressure gas exchanges excess heat with the incoming steam from a boiler and continues onward to a condenser. Once cooled, the high-pressure gas goes through a methanol separator, after which the carbon dioxide-rich gas is sequestered underground or is re-used. The remaining hydrogen-rich gas is combusted through a gas turbine. The gas turbine provides power to a generator and also regenerative heat for the boiler. The generator converts mechanical energy into electricity, which is transferred to the electric grid.
It is an object of the present invention to provide a system for use in hydrocarbon recovery that places a high purity carbon dioxide source close to the hydrocarbon-bearing formation.
It is another object of the present invention to provide a system for introducing carbon dioxide for use in hydrocarbon recovery which is portable.
It is still another object of the present invention to provide a system for producing carbon dioxide for use in hydrocarbon recovery that can be permitted as a minor emission source.
It is still a further object of the present invention to provide a system for producing carbon dioxide for use in hydrocarbon recovery which can be delivered in short order to a desired location.
It is a further object of the present invention to provide a system for producing carbon dioxide for use in hydrocarbon recovery that allows power to be sold into the power grid and for use in the enhanced oil recovery operations.
It is still another object of the present invention to provide a system for producing carbon dioxide for use in hydrocarbon recovery in a manner that is environmentally beneficial.
It is still a further object of the present invention to provide a system for producing carbon dioxide for use in hydrocarbon recovery which minimizes site work and field construction costs and equipment.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.